Diesel engine



1937. v v G. E. RAMs-r50 2,090,735 I DIESEL ENGINE: I

Filed Nov. 1, 1933 4 Sheets-Sheet 1 (lttotnegs Aug. 24, 1937.

4 Sheets-Sheet 2 Zhwentor ym 2% E.W

(Ittornegs Aug. 24, 1937. a. E. RAMSTAD' DIESEL ENGINE 1 Filed Nov. 1, 1933 4 Sheets-Sheet 3 EZFIIIIIIIII attorneys Aug; 1937. G. E. RAMSTAD 2,090,735

DIESEL ENGINE Filed Nov. 1, 1933 4 Sheets-Sheet 4 Zhwentor Pa/(LOW Baum/slab attorneys Patented Aug. 24, 1937 UNITED" STATES PATENT OFFICE DIESEL ENGINE Application November 1, 1933, Serial No. 696,253

13 Claims.

This invention relates to internal combustion engines and is particularly applicable to Diesel engines of the four cycle type. The general object of the invention is to provide a reversing gear for four cycle engines in which the cam shaft is not shifted axially or otherwise, and in which the operating-mechanism is simple and rugged in construction.

In a four cycle Diesel .engine there are three events that must be coordinated for forward and reverse running, 1) fuel-injection, (2) the opening and closing motions of the exhaust valve, and (3) the opening and closing motions of the inlet valve. In the following discussion reference will be made to positive injection of the fuel, but without implying necessary limitation to positive injection since the broad principles of the invention are more generally applicable.

The principal feature of novelty is the use of a single symmetrical cam for forward and reverse running, in conjunction with a single rocklever (or its equivalent) having two follower rollers, such rollers being selectively brought into coactive relation with the cam by shifting the valve or pump push rod (or its equivalent) relatively to the rock lever. While this arrangement might be provided for each of the three devices, fuel pump, exhaust valve, and inlet valve, its application to only two of these three devices is strictly necessary, and the simplest arrangement so far devised (and hereinafter described in detail) involves its application to the exhaust and inlet valves, the fuel pump being actuated by a single cam having a follower whose relation to the cam is unchanged for forward and reverse running. This last arrangement is possible because the fuel pump is single acting, and will perform its delivery stroke at different angular positions of the cam shaft in the two directions of rotation, if actuated by a suitably 'designed {symmetrical cam. An important reason for preferring the arrangement just described, is that if the shifting arrangement be applied to a different two of the three mechanisms, say the fuel pump and the exhaust valve, the follower of the inlet valve remaining in fixed relation to its cam, it has been found necessary to introduce a lost motion connection in the cam shaft drive (as has heretofore been done with other reversing gears) to ensure proper timing and sequence of events. Such lost motion connection is often undesirable and is unnecessary in the preferred arrangement.

The invention also contemplates in addition to 5 and in conjunction with the reverse gear, a controlling gear which has a stop position, an air starting position, and a range of running positions in which the quantity of fuel fed per cycle is varied. The reverse gear and controlling gear are interlocked so that the controlling gear can 5 be moved from stop position only when the reverse gear is in either its forward or reverse setting, and when so moved from stop position, locks the reversing gear.

Another feature of the invention is the con- 10 nection of a multiple unit air starting distributing valve, for actuation by the reversing gear and the controlling gear.

Another feature is a very simple arrangement of overspeed governor. 15

The preferred embodiment of the invention as applied to a six-cylinder vertical marine type engine will now be described.

In the drawings:

Fig. 1 is a fragmentary end elevation of an engine having the invention applied, parts of the reversing and control mechanisms being shown in dotted lines, and a portion of the air starting valve mechanism being shown in section.

Fig. 2 is a fragmentary side view of the engine, drawn on a somewhat smaller scale, the view being partly in elevation and partly in vertical section.

Fig. 3 is a view on a larger scale and in vertical section showing portions of the reversing gear and control gear. The plane of section is parallel with the axis of the crank shaft of the engine, and parts are broken away, so that the exhaust and inlet valve cam mechanisms and the fuel pump mechanism for only one cylinder are shown. V

Fig. 4 is a fragmentary view showing how the control mechanism is connected with the master valve of the airstarting unit.

Fig. 5 is a plan view of one of the fuel pumps, showing its connection with the control gear so that motion of the latter will vary the quantity of fuel delivered.

Fig. 6 is a vertical axial section through one 45 cylinder and its related mechanism, the plane of section being at right angles to the crank shaft and cam shaft. v

Fig. '7 is a fragmentary view showing the exhaust cam, its follower and push rod in the position of Fig. 6. v

Fig. 8 is a similar view showing the inlet cam, its follower and push rod, in the position of Fig. 6.

Fig. 9 is a similar view showing the fuel pump actuating cam, its follower and push rod, in

the position of Fig. 6.

In Figs. 6 to 9 inclusive, the parts are shown set for forward running. The exhaust valve is 5 about to open so that the piston is approaching the crank end dead point on its working stroke.

The general construction of the engine may conform to known practice, and in any event is not the subject of the present invention.

10 Hence the main components will be merely iden- The frame structure H carries a cylinder unit l2 having liners l3 for the individual cylinders and individual cylinder heads l4. In each cylin- 15 der is a trunk piston l5 connected by connecting rod IS with an appropriate crank of the crank shaft H. The engine is assumed to have six cylinders and accordingly the crank throws are 120 apart. The engine has a cam shaft l8 driven from the crank shaft at half crank shaft speed, by a gear train not illustrated except for gear I9 on shaft l8.

Each cylinder head is equipped with a fuel injecting nozzle 2| of known form intended for positive injection of the fuel into the cylinder when the fuel (oil) is delivered to it under pressure by a timed fuel injecting pump also of known form. This nozzle is at the center of the cylinder head.

30 An air starting valve housing 22, which contains a piston operated inlet valve of known form, for starting air is also mounted in each cylinder head l4.

Each cylinder head l4 also has anexhaust valve 35 and an inlet valve. The exhaust valve is mounted in a removable cage 23 (see Fig. 2). The valve is of the poppet type and opens inward against the resistance of spring 24 which reacts against valve stem 25. The inlet valve is similar, having 40 a cage 26, spring 21, and stem 28. These two valves are actuated by rocker arms 29 and 3| both carried by a journal pin 32 supported by an interposed bracket 33. The bracket 33 is bolted to the cylinder head. f Q

45 The moving parts are enclosedby removable covers 34 which give access to .the' prank: case, removable covers 35 which give access to the cams, push rods and reversing shaft, and removable covers 36 which give access to the'mech- 50 anism mounted on the heads l4.

There is a fuel pump 31 for each cylinder. Each pump is closely associated with its cylinder and is driven by a corresponding cam on the engine cam shaft I8. .These pumps are of the single acting plunger type delivering fuel oil whe'n the plunger moves upward. The discharge of each pump is connected by a corresponding pipe 38 with the corresponding fuelinjecting nozzle 2|. Each pump 31 is equipped with some 60 adjustable means to vary the quantity of fuel.

delivered on each stroke of the pump. Such adjustable means may take various known forms and is exemplified in the drawings (see Figs. and 6) by the longitudinally shiftable rod 39. 65 Since both the pump and the adjusting means are well known in the art and have been embodied in various forms, detailed illustration is deemed unnecessary.

Mounted on the end of the engine adjacent the 7 0 maneuvering gear, which will shortly be described,

is an air starting valve unit, indicated generally by the numeral 4| applied to its case (see Fig. 1).

Generally stated, this mechanism comprises a plurality of piston valves, one for each cylinder.

75 and means for operating them in timed sequence for each direction of running. Each piston valve is connected to the air starting valve housing 22 of a corresponding cylinder by a corresponding 6 to open the corresponding air starting valve in what would (in normal running) be the combustion stroke of the corresponding cylinder, and then exhausting to allow the starting valve to close. The exhaust of starting air from the engine cylinder is controlled by the exhaust valve of such cylinder.

The air starting mechanism is reversible, there being two reversely timed cams for each piston valve, and the starter shaft which carries these cams being shlftable axially to bring one or the other into .coactive relation with its starting valve. The various piston valves are spring urged away from their cams and are forced into coactive relation with their cams by the admission of starting air. Consequently, when the starting air is cut off the piston valves move out of coactive relation with their cams, leaving the starter shaft free to be shifted.

Carried by the engine cam shaft I8 is a spiral gear 43. This drives at the same angular velocity another spiral gear 44. Gear 44 turns in a hearing 45 and is held against motion in an axial direction. Splined in the gear 44 and shiftable axially therein is the starter shaft 46 which carries a plurality of-pairs of cams, one pair for each starting valve. These cams are designated by the numerals 41 and 48, the cams 41 being forward running cams and the cams 48 being reverse running cams.

In Fig. 1 the starter shaft 46 is shown to the right in the position for forward running so that the various cams 41 are positioned under the operating plungers49 of the various air valves.

The air va'lveproper consists of a piston head having' 'aireducedfl middle portion 5|. When the plunger uiisjperinitted to move downward by its I in the valve head connects the e ading fromany suitablesource of compressed ir with a port 53 which is connected byjacorresponding pipe 42 with the corresponding' starting, valve ;housing 22. When the plungers' are 'in"'their' upward or inert position, as shown, the recess 5| connects the port 53 with an exhaust or vent port 54 leading to the atmosphere, so thatthe pipes-42 are all vented thus causing closure of all the starting valves. At such time the supply of ports 52 are all blanked.

In Fig. 1 the starting mechanism is shown in its inert position in which the plungers 49 are all urged upward to their limit of motion by the springs 55 which encircle them. Consequently,

. the plungers 49 are clear of the cams 41 and 48.

A master air valve 56 having a reduced central portion 5'! controls the operation of the air starting mechanism. When the valve 56 moves downward it connects an air supply port 59 with a passage 6|. The passage 6| not only leads to all the supply ports 52 but is also connected by a passage 62 with the space 63 above all the plung-' ers. Consequently, when the valve 56 is moved downward to admit air to the passage 6|, the air pressure acting on the upper ends of the plungers overpowers the springs 55 and moves the plungers 49 into coactive relation with the cams 41 or the cams 48, whichever may then be in operative position.

When the valve 56 is moved upward, the reduced portion 51 connects the port 6| with a. vent port 64, which, as clearly shown in Fig. 1, is in free communication with the vent ports 54 already described.

The mechanism indicated generally by the numeral 65 in Fig. 1 is a force feed lubricator.

Referring now particularly to Figs. 6 to 9 inclusive. The cam shaft I8 is provided with a group of three cams for each working cylinder. These are fuel cam II, inlet cam I2, and exhaust cam I3. It will be observed that these three cams are each symmetrical with reference to a diameter. The diameter of symmetry of the inlet and exhaust valve cams is shown as lying in the same plane passing through the axis of the cam shaft, and this is for the reason that the rockers through which motion is taken from the cam, are mounted on concentric axes. This might or might not be the case, according to the design of the particular engine. Consequently, so far as the broad principles of invention are concerned, it is not necessary that the inlet and exhaust cams be angularly spaced from each other exactly as shown. As shown in this particular embodiment the diameter of symmetry of the fuel cam 'II is displaced angularly from the diameters of symmetry of the inlet and exhaust cams to compensate for the different location of its follower roller.

The follower roller of the fuel cam II is indicated at I4 and is guided by a radius link 15 which turns on a journal I6. The journal I6 is fixed so that the path of the roller I4 is always the same. The roller I4 is carried by a push rod 11 which is connected to the displacing plunger of the fuel pump 31. The cam II is made up of two arcuate dwell portions of different radii and these are connected by inclined portions so located that as the cam shaft turns in respectively reverse directions one or the other will impart upward motion to the roller 14 at the proper time for discharge of fuel into the cylinder. It has been said that the cam II" is symmetrical with respect to a diameter. This is approximately but not strictly true, for it is sometimes desirable to introduce slight modifications of form to compensate for the arcuatepath of the axis of roller 14.

The inlet cam 12 actuates a rocker I8 carried on a journal pin I9. The rocker I8 carries two follower rollers 8| and 82. The follower roller 8I contacts the cam I2 for forward running and the follower roller 82 for reverse running. The two rollers are so spaced that the mere shifting of the rock lever I8 positions the respective rollers correctly with respect to the cam for corresponding directions of rotation.

Such shifting of the rocker I8 is produced by moving the push rod 83 to one or the other side of the journal I9. To permit such motion, push rod 83 is provided with a roller 84 at its lower end and this roller contacts a V-shaped track 85 formed on the rock lever. The upper end of the push rod 83 is connected to the inlet valve rocker 3| so that when the rod 83 is forced upward'the valve is forced downward and opened. A coiled tension spring 86 is provided to make' sure that the roller 84 will be held in close contact with the track 85.

The exhaust cam I3 coacts with a rocker member 81 also pivoted on the journal pin I9 and also having two follower rollers. In this case, however, the positions of the forward follower roller and the reverse follow'er roller are interchanged, the forward follower roller being shown at 88 and the reverse follower roller at 89. These rollers are brought selectively into coactive relation with the cam 13 by shifting the push rod 9I to one or the other side of the journal pin I9. The push rod 9I isv connected to the exhaust valve rocker 29 which is equipped with a spring 92 having a function similar to that of the spring 86.

At the lower end of the push rod 9| is a roller 93 which coacts with a track 94 on the rocker81. The track 94 differs, however, from the track 85 to the extent that at its middle it is formed with a boss or a rise 95. This is so dimensioned that in mid-gear position, i. e., a position intermediate forward and reverse positions, all the exhaust valves will be held open slightly permitting the engine to be barred over without compression.

The position of the push rods 83 and SI is controlled by the position of a reversing shaft 96. Thissh'afthas two cranks for each engine cylinder, the cranks being spaced apart, one set of cranks being connected by links 91 withthe exhaust pushrods9l of the various cylinders, and the other set ,of cranks being connected by links 98 with the push rods 83 of the various cylinders. The cranks are so dimensioned that if the shaft 96 be turned back and forth through 180 the push rods are shifted back and forth suitable distances across the fulcrum pin I9. The inlet push rods and the exhaust push rods move simultaneously in respectively reverse directions.

A study of the layout given in Figs. 6 to 9, will show that this shifting of parts will reverse the sequence of events while maintaining identical timing relatively to piston position.

The shaft 96 is rotated to set it for forward or reverse running by means of a hand wheel 99 see Figs. 1 and 2) which may be latchedin either limiting position or in mid-gear position by a manually releasable detent II. The wheel 99 is connected to drive the shaft 96 at reduced angular velocity by atrain consisting of a pair of bevel gears I02, a vertical intermediate shaft I83 and a pair of motion-reducing bevel gears I04.

The shaft 96 carries at its forward end a pointer I05 which indicates the position of the reverse shaft. Near this pointer is also carried'a crank I06 which is connected by connecting rod I01 and rock lever I88 with a collar I09 swiveled on the end of shaft 46. The parts are so dimensioned that when the shaft 96 is turned from forward running to reverse running position the crank I96 will shift the shaft 46 sufficiently to interchange the cams 41 and 48. From this it follows that a single reversing means, i. e., the wheel 99, not only sets the inlet and exhaust valves for forward or reverse running, as the case may be, but also simultaneously sets the air starting gear to start the engine forward or backward.

The control of the energy input of the engine is effected by adjusting the members 39 forming parts of the fuel pumps, and these are connected to be adjusted in unison by a rod. III which is slidable longitudinally in guides I I2; The rod III is connected by brackets II3 fixed thereon and links I I4 with the various fuel controlling members 39 of the fuel feed pumps 31. The rod I I I is moved to the right relatively to Figs. 2 and 3,

to reduce the amount of fuel fed, and at the exr the rod III. Normally the governor H5 does not affect the red I I I, but if the speed becomes excessive, the lost motion permitted by the pin and slot connection I I8 will be exceeded and the governor 6 will take control of the rod III to prevent oversmed. This action is possible because the manual control mechanism operates the rod III permissively and not positively in a speed increasing direction. This operative connection will .0 now be described.

At its left hand end the rod III is connected through a link I2I with one arm I22 of a bell crank lever, whose other arm carries a roller I23 coacting with a cam I24. Engagement of the roller I23 with the cam I24 is effected by the tension spring I25. The cam I24 is fixed on a shaft I26. Also fixed to this shaft is an arm I21 which is connected by link I28 with an arm I29. The arm I29 is fixed on a shaft [3| to which is also fixed controller handle I32. This controller handle swings over an arc I33 which has a series of latch holes I34 defining the normal operative range of the engine. The handle latch is indicated at I35 in Fig. 3.

In the lowermost position of the handle I32 (see Fig. 3) the engine will stop for the reason that the cam I24 holds the roller I23 elevated and thus moves rod III to the right far enough to cut off the supply of fuel. In the range of positions represented by the holes I34, roller I23 will be in contact with the left side of the cam I24, so that the higher the lever I32 the lower the roller I23 will be and the more fuel will be fed to the engine.

The vertical position of the handle I 32 is the air starting position, and in this position, the master air valve 56 of Fig. 1, is moved to its lowermost.position to supply airto the air starting mechanism. The connection for producing this result is shown in detail in Fig. 4.

An arm I36 on shaft I26 is connected by a link I3'I with the upper end of the valve 56 and the angle of the 'arm I36 and the lap of valve 56 are so chosen that the valve will not commence to open until just before the control handle 32 reaches its vertical position.

It will be observed that in the air starting position the roller I23 is lowered so that fuel will be fed to the engine through the fuel pump and injecting nozzles while the air starting valves are operating. This is believed to facilitate starting and has been proposed heretofore, but it is not material to the present invention that fuel oil be injected at this time. If such injection is not desired the cam I24 ma hbe redesigned so that in air starting position the roller I 23 will be held elevated. This result can be effected in a number of specificaly different ways, some of which involve changing the sequence of the stop, run and start positions relatively to sector An interlock is afforded between the reversing gear and the controlling gear. The interlock comprises two notched disks. Fixed on the shaft 05 96 is a large disk I4I whose edge intersects the edge of a smaller disk I42 on the shaft I26. Since the shaft 96 has two operative positions 180 apart, its edge is provided with two notches I43 and I44 (see Fig. 1). The disk I42 is provided with a single notch I45 which registers with the edge of the disk I4I only when the control handle I32 is in its lowest or stop position. From this it follows that when the controller handle is in stop position the reversing gear can be moved at will between forward and reverse positions and in all. positions intermediate these two locks the controller handle against motion from stop position. If the reversing gear be in either forward or reverse positions the controller may be moved through the running range and to starting position, but its initial motion from stop position locks the reversing gear against motion from whichever of its two limiting positions it may then occupy. This not only protects the engine reversing gear against faulty manipulation, but it also insures that the air starting plungers 49 will be retracted upward before the shaft 46 can be shifted.

The rotation of the shaft 96 is limited to 180 and the wheel 99. is provided with proper legends such as Astern and Ahead with arrows indicating the direction of rotation to set the gear for the desired direction of engine rotation.

The operation of the device will be readily understood from the description already given, but will be summarized briefly.

With the controller handle I32 in stop position (see Fig. 2) the reversewheel may be turned in either direction after releasing the latch I0 I. the two limiting positions, described as Astern and Ahead for a marine engine, the controller handle I32 may be shifted to air starting position to put the engine in motion, and from air starting position to the running range of positions. The wheel 99 can not be moved from Astern or Ahead position, as the case may be, after the handle I32 has been moved from stop position. With the handle I32 in stop position, the reversing wheel may be moved to a mid-position, in which the exhaust valves are held open by the bosses on the rockers 87 and the controller handle is locked in Step position. This setting is used only when it is desired to bar the engine over.

While one embodiment of the invention has been described in considerable detail, it is to be expressly understood that the use of a rocking member provided with two followers which are shiftable selectively into coactive relation with the single cam for forward and reverse running, is generally applicable. In an engine in which three events must be reversely timed, it is possible, as disclosed, to use this mechanism to com trol only two of the three events, but so far as the broad invention involving the use of the rocker with a plurality of followers is concerned, it is immaterial whether the scheme be used as to one or more events.

What is claimed is,-

1. The combination of a reversible four cycle engine having a reciprocating piston, a crank shaft driven thereby, and a cam shaft driven at half crank shaft speed; an inlet valve; an exhaust valve; an inlet cam and an exhaust cam on said cam shaft; a pair of tiltable members, one for each cam, each such member having two followers which are brought selectively into coactive engagement with the same corresponding cam by reversely tilting themember, said foilowers on each member being each positioned relatively to its cam, when engaged therewith, to produce appropriate timing of the corresponding valve for forward and reverse running respectively; actuators each connected to actuate a corresponding valve, and each shiftable between two F positions in which it engages the corresponding tiltable member and is driven thereby, and in which respectively, it tilts said corresponding member in opposite directions, and means for simultaneously shifting said actuators, said means comprising a maneuvering shaft having cranks operatively connected with corresponding ones of said actuators, the parts being so dimensioned and arranged that the maneuvering shaft turns through an angle of substantially 180 in shifting said actuators between said two positions.

2. The combination of a reversible four cycle engine having a reciprocating piston, a crank shaft driven thereby, and a cam shaft driven at half crank shaft speed; an inlet valve; an exhaust valve; an inlet cam and an exhaust cam on said cam shaft; 2. pair of tiltable members, one for each cam, each such member having two followers which are brought selectively into coactive engagement with the same corresponding cam by reversely tilting the member, said followers on each member being each positioned relatively to its cam, when engaged therewith, to produce appropriate timing of the corresponding valve for forward and reverse running respectively; actuators each connected to actuate a corresponding valve, and each shiftable between two positions in which it engages the corresponding tiltable member and is driven thereby, and in which respectively, it tilts said corresponding member in opposite directions; and means for simultaneously shifting said actuators in relatively reverse directions.

3. The combination of a reversible four cycle engine having a reciprocating piston, a crank shaft and a cam shaft driven at half crank shaft speed; a single acting reciprocating fuel injecting means; an inlet valve; an exhaust valve; a

driving. cam for the fuel injecting means, an inlet cam and an exhaust cam, all mounted on the cam shaft and each characterized by substantial symmetry with reference to their respective diameters; a follower guided in the same path in both forward and reverse running, coacting with the fuel cam and connected to reciprocate the fuel injecting means; a pair of tiltable members, one for the inlet cam and one for the exhaust cam, each such member having two followers, which are brought selectively into coactive engagement with the corresponding cam by reversely tilting the. member, said followers on each member being each positioned relatively to its shaft and a cam shaft driven at half crank shaft.

speed; a single acting reciprocating fuel injecting means; an inlet valve; an exhaust valve; a driving cam for the fuel injecting means, an inlet cam and an exhaust cam, all mounted on the cam shaft and each characterized by substantial symmetry with reference to their respective diameters; a follower guided in the same path in both forward and reverse running, co'acting with the fuel cam and connected to reciprocate the fuel injecting means; a pair of tiltable members, one for the inlet cam and one for the exhaust cam, each such member having two followers, which are brought selectively into coactive engagement with the corresponding cam by reverse- 75 1y tilting the member, said followers on each member being each positioned relatively to its cam, when engaged therewith, to produce appropriate timing of the corresponding valve for forward and reverse running respectively; actuators each connected to actuate a corresponding valve, and each shiftable between two positions in which it engages the corresponding tiltable member and is driven thereby, and in which respectively, it tilts said corresponding member in opposite directions; and means for simultaneously shifting said actuators in relatively reverse'directions.

5. The combination defined in claim 4, in which the means for shifting said actuators comprise a maneuvering shaft having two cranks spaced 180 apart, each crank connected with a corresponding actuator, the parts being so dimensioned that the maneuvering shaft turns through an angle of substantially 180 in shifting said actuators between said two positions.

6. In a reversible engine, the combination of a cylinder; a piston; a crank shaft driven by the piston; fuel injecting means; an inlet valve; an exhaust valve; -a cam shaft driven at half crank shaft speed; a fuel cam; an inlet, cam and an exhaust cam all mounted on said cam shaft; and follower mechanisms respectively actuated by said cams and operatively associated respectively with the fuel injecting means, the inlet valve and the exhaust valve, one of said follower mechanisms being arranged to move in an unchanged path for forward'and reverse directions of rotation of the crank shaft and the other two follower mechanisms being variable with respect to their point of coaction with their respective cams as to forward and reverse directions of rotation of the crank shaft.

7. The combination defined in claim 6, in which the follower mechanism which moves in an unchanged path is that associated with the fuel injecting means.

8. The combination of a reversible engine having a reciprocating piston, a crank shaft driven by said piston, and a rotary cam shaft driven by said crank shaft; a normally closed distributing valve adapted to be operated in timed relation to the reciprocation of said piston; a cam on said cam shaft; a tiltable member having two cam followers which are brought selectively into coactive relation with said cam by reversely tilting said member, said followers each being positioned relatively to the cam when-in engagement therewith to produce appropriate timing of the distributing valve relatively to piston movement in forward and reverse running respectively; an actuator connected to actuate said distributing valve and shiftable between two positions in which it engages said tiltable member and is driven thereby, and in which, respectively, it tilts said member in opposite directions; and means for so shifting said actuator, said tiltable member being so formed as to engage said actuator when the latter is in a position intermediate said two positions and cause the actuator to hold said valve open irrespective of the position of said cam.

9. The combination of a reversible four cycle engine having a reciprocating piston, a crank shaft driven thereby, and a cam shaft driven at half crank shaft speed; an inlet valve; an exhaust valve; an inlet cam and an exhaust cam on said cam shaft; a pair of tiltable members, one for each cam, each such member having two followers which are brought selectively into coactive engagement with the corresponding cam by reversely tilting the member, said followers on each member being each positioned relatively to its cam, when engaged therewith, to produce appropriate timing of the corresponding valve for forward and reverse running respectively; actuators each connected to actuate a corresponding valve, and each shiftable between two positions in which it engages the corresponding tiltable member and is driven thereby, and in which respectively, it tilts said corresponding member in opposite directions; and means for simultaneously shifting said actuators in relatively reverse directions, said means comprising a maneuvering shaft having two cranks spaced 180 apart, each crank being operatively connected with a corresponding actuator, the parts being so dimensioned and arranged that the maneuvering shaft turns through an angle of substantially 180 in shifting said actuators between said two positions.

10. The combination of a reversible four cycle engine having a, reciprocating piston, a crank shaft driven thereby, and a cam shaft driven at half crank shaft speed; an inlet valve; an exhaust valve; an inlet cam and an exhaust cam on said cam shaft, said cams each being symmetrical with reference to a common plane passing through the axis of the cam shaft and having their raised portions displaced 180 from each other; a pair of tiltable members, one for each cam, each such member having two followers which are brought selectively into coactive engagement with the corresponding cam by reverselytilting the member, said followers on each member being so positioned relatively to the corresponding cam, when engaged therewith, as to produce appropriate timing of the corresponding valve for forward and reverse directions of running respectively; actuators each connected to actuate a corresponding valve and each shiftable between two positions in which it engages the corresponding tiltable member and is driven thereby, and in which respectively it tilts said corresponding member in relatively reverse directions; and means for simultaneously shifting said actuators in relatively reverse directions.

11. The combination of a reversible four cycle engine having a reciprocating piston, a crank shaft and a cam shaft driven at half crank shaft speed; a single acting reciprocating fuel inject- 0 ing means; an inlet valve; an exhaust valve; a

driving cam for the fuel injecting means, an inlet cam and an exhaust cam, all mounted on the cam shaft and each characterized by substantial symmetry with reference to their respective diameters, the diameters of symmetry of the inlet and exhaust cams lying in a common plane passing through the axis of the cam shaft and the raised portions of the last-named cams being diswith, to produce appropriate timing of the corresponding valve for forward and reverse running respectively; actuators each connected to actuate a corresponding valve, and each shiftable between two positions in which it engages the corresponding tiltable member and is driven thereby, and in which respectively it tilts said corresponding member in opposite directions; and means for simultaneously shifting said actuators.

12. The combination of a reversible four cycle engine having a reciprocating piston, a crank shaft and a cam shaft driven at half crank shaft speed; a single acting reciprocating fuel injecting means; an inlet valve; an exhaust valve; a driving cam for the fuel injecting means, an inlet cam and an exhaust cam, all mounted on-the cam shaft and each characterized by substantial symmetry with reference to their respective diameters, the diameters of symmetry of the inlet and exhaust cams lying in a common plane passing through the axis of the cam shaft and the raised portions of the last named cams being displaced 180 from each other; a follower guided in the same path in both forward and reverse running, coacting with the fuel cam and arranged to actuate the fuel injecting means; a pair of tiltable members, one for the inlet and the other for the exhaust cam, said members tilting on coincident axes and each such member having two followers which are brought selectively into coactive engagement with the same corresponding cam by reversely tilting the member, said followers on each member being positioned relatively to such corresponding cam when engaged therewith, to produce appropriate timing of the corresponding valve for forward and reverse running, respectively; actuators each connected to actuate a corresponding valve, and each shiftable between two positions in which it engages the corresponding tiltable member and is driven thereby, and in which respectively it tilts said corresponding member in opposite directions; and means for simultaneously shifting said actuators in relatively reverse directions.

13. The combination of a reversible four cycle engine having a reciprocating piston, a crank shaft-driven thereby, and a cam shaft driven at half crank shaft speed; an exhaust valve; an exhaust cam on said cam shaft; a tiltable member, such member having two followers which are brought selectively into coactive engagement with the exhaust cam by reversely tilting the member, said followers being each positioned relatively to said cam, when engaged therewith, to produce appropriate timing of the exhaust valve for forward and reverse running respectively; an actuator connected to actuate said exhaust valve, and shiftable between two positions in which it engages the tiltable member and is driven thereby, and in which respectively, it tilts said member in opposite directions; and means for shifting said actuator, the tiltable member being so formed that, irrespective of the position of the exhaust cam, it displaces the corresponding actuator and holds the exhaust valve open as the actuator shifts between said two positions.

GEORGE E. RAMSTAD. 

